<?php
if ($this->ok == 'ok') 
{
  echo 'ok';
}
elseif (is_array($this->fallo)) 
{
  ?>
<ul>
  <?php foreach ($this->fallo as $fallo): ?>
  <li> <?= $fallo; ?> </li>
  <?php endforeach; ?>
</ul>
  <?php
}
elseif (is_string($this->fallo)) 
{
  echo $this->fallo;
}
?>